Various types of self-piercing fasteners have been developed in the past in an attempt to obtain a strong union between the fastener and the part to which it is attached. For example, one successful prior art application of this type of fastener construction consists of a threaded nut and panel assembly which receives a fastener, such as a bolt, wherein the nut and panel are secured together by a die press in a single machine operation. The nut utilized in this type of assembly is commonly referred to in the art as a "pierce nut".
Pierce nuts of the type disclosed above and suitable for installation in a panel are disclosed in U.S. Pat. Nos. 3,439,723, issued Apr. 22, 1969 and 3,648,747, issued Mar. 14, 1972. As described in these prior patents, the threaded nut includes a central pilot portion having sharp edges which are used to pierce a sheet metal panel during a die punch operation in which the pilot portion of the nut punches through the panel to form an opening in the panel within which the nut is received. The nut includes undercut re-entrant grooves formed on opposite sides of the pilot portion which are filled with the edges of the panel by swagging or otherwise deforming the panel into such grooves. The re-entrant grooves, which are filled with panel metal, form a strong union between the nut and panel and serve to restrain the nut-panel assembly against separation.
The above described nut-panel assembly and method of nut installation is particularly efficient and suitable for a high production environment. In some cases, automated nut installation is facilitated by forming the nuts in a strip wherein the nuts are interconnected by frangible connections which are severed by automatic equipment as the nuts are successively removed from the strip and installed in a panel.
In many fastener applications, such as high volume, production line assembly, the speed with which the fastener and associated parts can be assembled in an important factor. Threaded type fasteners typically require more time and dexterity to assemble compared to other, "quick-action" nonthreaded fasteners. One type of known quick-action fastener employs a nutlike female portion which includes an aperture having a lock wire extending across the aperture, and a male portion having a spiral cam slot which receives and coacts with the lock wire to hold the male portion within the female portion. The nut like female portion is typically defined by a formed sheet metal body and in some cases may include a pair of outwardly extending flanges which engage the face of a panel surrounding an opening therein in order to hold the female portion on the panel. This type of construction is not well suited to a high production assembly environment since at least two operations are required for installing the nut like female portion: forming an opening in the panel and positioning and inserting the nut like female portion through the opening. Moreover, the resulting assembly is inferior in that the nut like female portion does not form an integral union with the panel, but rather some tolerance therebetween exists in order to allow passage of the female portion through the panel opening. Finally, these prior art fasteners are not suitable to be manufactured in strips to facilitate rapid installation thereof by automated equipment.
Accordingly, it is a primary object of the present invention to provide a quick action fastener suitable for high volume installation in panels and the like which overcomes each of the deficiencies of the prior art discussed above.